Various embodiments described herein relate generally to semiconductor devices and methods of fabricating the same. More particularly, various embodiments described herein relate to semiconductor devices that can provide improved p-type metal-oxide-semiconductor (PMOS) performance, and methods of fabricating the same.
With increasing demand for high speed semiconductor devices, a metal-oxide-semiconductor field effect transistor (MOSFET) including a high-k gate insulating layer and a metal gate electrode has been extensively studied. Recently, a way of changing a crystal structure of a channel region of MOSFET has been proposed, using tensile and/or compressive stress layers, so as to improve an electric characteristic of MOSFET. However, there have been some technical difficulties in enhancing the electric characteristics for both types of MOSFET (i.e., n- and p-type MOSFETs).